Conventionally, in ATM (Automatic Teller Machine) or the like at banks, when a banknote is received, the type thereof needs to be judged. Therefore, there has been known a paper sheet recognition technique for recognizing the type of paper sheets such as banknotes and securities highly accurately.
For example, Patent Document 1 discloses a paper sheet recognition method in which for each combination of two kinds of judgment candidates, an effective read position, at which a distance between distributions is largest between distributions of reference features of both of the judgment candidates, is extracted from a plurality of predetermined read positions. The distance from the feature of a paper sheet to be tested, which can be acquired only from the effective read position, is acquired respectively for a combination in which the distance between distributions at the effective read position acquired for each combination of the two kinds of judgment candidates is largest. A narrowing-down process is then performed for excluding the kind of paper sheet with the acquired distance being larger from the judgment candidate, and the kind of the paper sheet is judged by repeating the narrowing-down process for the remaining judgment candidates.
Patent Document 1: Japanese Patent Application Laid-open No. 2001-273541